Fiber Fabry-Perot Interferometric Sensor Using Bragg Gratings in Polarization Maintaining Fiber

A fiber Bragg grating (FBG) has been used as a sensor head for the measurement of temperature and static strain. However, a standard FBG sensor, which is constructed on a single-mode fiber, cannot work well under conditions where both the temperature and strain change independently since the sensor has cross-sensitivity between them. The cross-sensitivity problem can be solved by using an FBG constructed on a polarization maintaining fiber (PM-FBG) instead of a standard FBG. In this paper, we report improvement on the resolution for the simultaneous measurement of temperature and static strain. A Fabry-Perot interferometer constructed with PM-FBGs (PM-FBG-FPI) is introduced as a sensor head. The fine structure of a PM-FBG-FPI reflection spectrum enables high-resolution detection of wavelength shifts. The resulting high-resolution measurements are demonstrated experimentally.